Various surgical procedures employ a catheter for the introduction of surgical tools, fluids or other materials into the body. For example, catheters are used for the introduction of items including but not limited to radiographic contrast materials, angioplasty balloons, fiber optic scopes, laser lights, and cutting instruments into the vessels, cavities, or tissues of a human body.
It is known to provide a catheter with an arrangement for steering through body vessels or cavities. For example, U.S. Pat. No. 5,437,636 to Snoke et al. discloses a catheter for use in body vessels or cavities having a housing and an elongated tube. The elongated tube has one end connected to the housing, extends outwardly therefrom and is formed of material of such a stiffness so as to normally maintain the elongated tube in a straight condition in the absence of an external force. An outer end portion of the elongated tube is relatively flexible. Guide wires are connected to the housing and extend outwardly through the elongated tube. The outer ends of the guide wires are connected to the flexible outer end portion of the elongated tube. A guide wire control mechanism is carried by the housing and cooperates with the guide wires for manually controlling the angular attitude of the flexible outer end portion of the elongated tube to thereby effectively “steer” the catheter. U.S. Pat. No. 5,473,636 is incorporated by reference as if fully set forth herein.
It is also known in the pertinent art to provide a steerable catheter with a locking mechanism for arresting the relative position of an elongated tube. In a conventional manner, a steering wheel is manually used to articulate the elongated tube for navigation through a vessel, cavity, or tissue of a patient. Manually releasing the steering wheel returns the elongated tube to its straight condition. At certain points during any particular surgical procedure, it may be desired to arrest the relative orientation of the elongated tube. At such time, the conventional locking mechanism is activated and movement of the steering wheel relative to the remainder of the catheter is effectively precluded.
While known locking mechanisms for steerable catheters have proven to be acceptable for their intended applications, they are all associated with limitations. Principally insofar as the present invention is concerned, maintaining a relative orientation of the elongated tube conventionally requires a secondary operation to activate a locking mechanism. Accordingly, it remains a need in the pertinent art to provide a retention mechanism for a steerable catheter that permits a surgeon to easily toggle between a first mode in which a steering wheel freely rotates and a second mode in which motion of the steering wheel is ratcheted.